Locals call it the 'altar field', yet no altar stone survives there. What remains instead is a low, roughly triangular platform of raised ground in the south-west corner, measuring about eight metres north to south and five metres east to west, rising just forty centimetres above the surrounding pasture. That modest elevation is, in all likelihood, where a priest once said Mass in secret.

Mass-rocks are among the quieter physical remnants of the Penal Laws, the body of legislation passed in Ireland from the late seventeenth century onward that severely restricted Catholic worship, among much else. With chapels prohibited or demolished, congregations gathered outdoors, often on remote hillsides or in sheltered fields, and a flat stone served as an improvised altar. The site at Commons fits this pattern precisely: pasture sheltered by trees, a raised patch of ground suited to a standing congregation, and a field name that preserved the memory of what happened there even after the stone itself disappeared. Two further details sharpen the picture. Built into the western end of the southern boundary wall is a small lintelled wall cupboard, roughly seventy centimetres wide, sixty high, and seventy-five deep, a recess of the kind that would have been well suited to storing the vessels and cloths required for the celebration of Mass. To the east of it, a holly tree grows out of a loose pile of small stones heaped against the same wall. Holly carries a long association with sacred sites in Ireland, and though the stones appear to have been gathered rather than arranged with any obvious intention, the combination of tree, stones, and cupboard clustered together along that boundary wall suggests this corner of the field held particular significance.